There are approximately 4000 coronary angiograms performed annually at the Hamilton General Hospital to diagnose and treat coronary artery disease. Many of the patients undergoing this procedure have mild kidney disease. Exposure to the contrast dye used in the procedure puts them at risk of worsening kidney function, a condition called contrast induced nephropathy (CIN) which is associated with significant morbidity and mortality. Many of these patients are also on an antihypertensive drug called an angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB). Their effects on the kidney during contrast exposure are not known. Our understanding of how the drug works leads us to believe that the use of these drugs around the time of contrast exposure may have detrimental effects on the kidney.